1. Field of the Invention
The present invention relates to a dynamic speaker, particularly to a structure of fixing a lead wire of a voice coil.
2. Description of the Related Art
A dynamic speaker is conventionally known among the types of a speaker. As shown in JP-A-6-178390, a dynamic speaker comprises a diaphragm having a voice coil attached on the back surface, and a frame disposed on the back side of the diaphragm and adapted to support the diaphragm at the periphery thereof. A pair of lead wire drawn from the voice coil is fixed to a pair of terminal member mounted on the back side of the frame by soldering or other means. The land portion of the terminal member where the lead wire is fixed has the shape of a plate extending along the surface of the frame.
If the frame is made of synthetic resin, part of the frame around the land portion is possibly melted and deformed by heat generated in the process of fixation.
An object of the present invention is to provide a dynamic speaker comprising a frame made of synthetic resin, which effectively prevents melting of part of the frame around the land portion.
The speaker of the present invention achieves the object by providing a hole or a notch in the frame.
A speaker of the present invention comprises:
a diaphragm;
a voice coil attached to the back surface of the diaphragm;
a frame made of synthetic resin, disposed on the back side of the diaphragm and supporting the diaphragm at the outer edge thereof; and
a pair of terminal member mounted on the frame and having a portion where a pair of lead wire drawn from the voice coil is fixed;
wherein the portion has the shape of a plate which extends along the surface of the frame, and
a hole or a notch is provided in the frame at the back side of the portion so as to expose the portion to the back space of the frame.
The word such as xe2x80x9cbackxe2x80x9d is used for the purpose of explanation to clarify the positional relationship of the members. The actual direction or orientation of the speaker when operated is not thereby limited.
Any type of xe2x80x9cdiaphragmxe2x80x9d and xe2x80x9cvoice coilxe2x80x9d may be used as far as applicable as an element of a dynamic speaker.
Any type of xe2x80x9cterminal memberxe2x80x9d may be used as far as the portion is made of conductive material and disposed along the surface of the frame. The terminal member may be integrally formed with the frame, or may be fixed on the frame by adhesive or screw.
The lead wire is fixed to the portion of the terminal member for electrical connection. Any type of fixing method is applicable such as soldering and thermo-compression bonding.
The phrase of xe2x80x9cextends along the surface of the framexe2x80x9d means that the surface of the land portion is substantially coplanar with or substantially parallel to the surface of the frame.
The xe2x80x9csurface of the framexe2x80x9d is not limited to a particular surface. It may be the upper surface, the lower surface, the outer surface or any other.
As described above, according to the speaker of the present invention, the pair of land portion having the shape of a plate is disposed along the surface of the resin frame. The frame has the pair of circular hole or notch on the back side of the pair of land portion formed so as to expose the land portion to the back space of the frame. Heat generated in the process of thermo-compression bonding is diffused to the back space of the frame via the circular hole or the notch.
This invention prevents melting of part of the frame around the land portion.
The supporting jig may be abutted against the back surface of the land portion via the circular hole or the notch. Therefore, heat generated in the process of thermo-compression bonding is immediately transmitted from the land portion to the supporting jig of higher conductivity. This effectively prevents melting of part the frame around the land portion.
The lead wire may be fixed to the land portion by thermo-compression bonding method. This eliminates a conventional soldering process and contributes to an environmental lead-free structure. This effectively reduces a space for fixation since a space for solder spot is not required. Continuity failure is also considerably lessened since this method provides more reliable continuity.
Further, since the thermo-compression bonding jig is stopped by the supporting jig, the land portion is prevented from sinking in the frame even when pressing force is applied from the thermo-compression bonding jig.
The xe2x80x9cthermo-compression bondingxe2x80x9d is a method applying heat and pressing force. Any type of heating method may be used as far as it melts the insulation coating of the lead wire so that the exposed core of the wire may be pressed against the land portion of the terminal member by pressing force. For example, the following three methods are applicable: 1) supplying current between the lead wires; 2) supplying current between the terminal member and a thermo-compression bonding jig holding the lead wire; and 3) pre-heating the jig and pressing the heated jig against the lead wire.
The pair of circular hole or notch may be so located as to be opposite to the thermo-compression bonded portion of the lead wire. Therefore, heat transmission from the land portion to the supporting jig is available via the shortest path, which prevents melting of the frame effectively. Further, pressing force of the thermo-compression bonding jig is directly received by the supporting jig which prevents sinking of the land portion in the frame effectively.
The pair of terminal member may be integrally formed with the frame by insert molding. This improves the mounting strength of the terminal member, and enables part of the terminal member to be easily protruded outside the speaker. The pair of hole located on the back side of the land portions may be formed by an insert holding member for positioning the pair of terminal member in a mold